1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
|
/*
* ChaCha20 256-bit cipher algorithm, RFC7539
*
* Copyright (C) 2015 Martin Willi
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*/
#include <crypto/algapi.h>
#include <crypto/chacha20.h>
#include <crypto/internal/skcipher.h>
#include <linux/module.h>
static inline u32 le32_to_cpuvp(const void *p)
{
return le32_to_cpup(p);
}
static void chacha20_docrypt(u32 *state, u8 *dst, const u8 *src,
unsigned int bytes)
{
u8 stream[CHACHA20_BLOCK_SIZE];
if (dst != src)
memcpy(dst, src, bytes);
while (bytes >= CHACHA20_BLOCK_SIZE) {
chacha20_block(state, stream);
crypto_xor(dst, stream, CHACHA20_BLOCK_SIZE);
bytes -= CHACHA20_BLOCK_SIZE;
dst += CHACHA20_BLOCK_SIZE;
}
if (bytes) {
chacha20_block(state, stream);
crypto_xor(dst, stream, bytes);
}
}
void crypto_chacha20_init(u32 *state, struct chacha20_ctx *ctx, u8 *iv)
{
static const char constant[16] = "expand 32-byte k";
state[0] = le32_to_cpuvp(constant + 0);
state[1] = le32_to_cpuvp(constant + 4);
state[2] = le32_to_cpuvp(constant + 8);
state[3] = le32_to_cpuvp(constant + 12);
state[4] = ctx->key[0];
state[5] = ctx->key[1];
state[6] = ctx->key[2];
state[7] = ctx->key[3];
state[8] = ctx->key[4];
state[9] = ctx->key[5];
state[10] = ctx->key[6];
state[11] = ctx->key[7];
state[12] = le32_to_cpuvp(iv + 0);
state[13] = le32_to_cpuvp(iv + 4);
state[14] = le32_to_cpuvp(iv + 8);
state[15] = le32_to_cpuvp(iv + 12);
}
EXPORT_SYMBOL_GPL(crypto_chacha20_init);
int crypto_chacha20_setkey(struct crypto_skcipher *tfm, const u8 *key,
unsigned int keysize)
{
struct chacha20_ctx *ctx = crypto_skcipher_ctx(tfm);
int i;
if (keysize != CHACHA20_KEY_SIZE)
return -EINVAL;
for (i = 0; i < ARRAY_SIZE(ctx->key); i++)
ctx->key[i] = le32_to_cpuvp(key + i * sizeof(u32));
return 0;
}
EXPORT_SYMBOL_GPL(crypto_chacha20_setkey);
int crypto_chacha20_crypt(struct skcipher_request *req)
{
struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
struct chacha20_ctx *ctx = crypto_skcipher_ctx(tfm);
struct skcipher_walk walk;
u32 state[16];
int err;
err = skcipher_walk_virt(&walk, req, true);
crypto_chacha20_init(state, ctx, walk.iv);
while (walk.nbytes > 0) {
unsigned int nbytes = walk.nbytes;
if (nbytes < walk.total)
nbytes = round_down(nbytes, walk.stride);
chacha20_docrypt(state, walk.dst.virt.addr, walk.src.virt.addr,
nbytes);
err = skcipher_walk_done(&walk, walk.nbytes - nbytes);
}
return err;
}
EXPORT_SYMBOL_GPL(crypto_chacha20_crypt);
static struct skcipher_alg alg = {
.base.cra_name = "chacha20",
.base.cra_driver_name = "chacha20-generic",
.base.cra_priority = 100,
.base.cra_blocksize = 1,
.base.cra_ctxsize = sizeof(struct chacha20_ctx),
.base.cra_alignmask = sizeof(u32) - 1,
.base.cra_module = THIS_MODULE,
.min_keysize = CHACHA20_KEY_SIZE,
.max_keysize = CHACHA20_KEY_SIZE,
.ivsize = CHACHA20_IV_SIZE,
.chunksize = CHACHA20_BLOCK_SIZE,
.setkey = crypto_chacha20_setkey,
.encrypt = crypto_chacha20_crypt,
.decrypt = crypto_chacha20_crypt,
};
static int __init chacha20_generic_mod_init(void)
{
return crypto_register_skcipher(&alg);
}
static void __exit chacha20_generic_mod_fini(void)
{
crypto_unregister_skcipher(&alg);
}
module_init(chacha20_generic_mod_init);
module_exit(chacha20_generic_mod_fini);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Martin Willi <martin@strongswan.org>");
MODULE_DESCRIPTION("chacha20 cipher algorithm");
MODULE_ALIAS_CRYPTO("chacha20");
MODULE_ALIAS_CRYPTO("chacha20-generic");
|
